Dental handpieces typically include a handpiece body, a coupler and a flexible supply connection. The handpiece includes a proximal end, a distal end and a body intermediate the proximal and distal end, the proximal end, the distal end and the handpiece body oriented in a substantially axial direction. An outer surface of the body is molded to be an ergonomic gripping area is so that the dental professional can comfortably grip the handpiece. The distal end has a head onto which a removable workpiece, such as a burr or a prophy-angle is attached. A coupler is assembled axially to the handpiece body, the coupler having a supply-end portion and a cylinder portion projecting from the supply-end portion. The cylinder portion of the coupler, which includes one or more diametral portions, extends in the axial direction into the handpiece body toward the distal end. The supply-end portion is positioned at the proximal end of the handpiece, and may project outward from the proximal end of the handpiece in a direction opposite the distal end. The supply-end portion usually is configured in accordance with an industry standard, here ISO 9168, so as to provide a substantially uniform attachment configuration with the flexible supply connection, the supply connection usually including a hose. The coupler may be molded into the handpiece so as to be integral with it, or it may be a separate, distinct piece removably attached to the handpiece. By integral is meant that the coupler is molded into the handpiece so that it cannot be readily removed from the handpiece, even though the coupler may be a separate component. The coupler usually is adapted to mate with a quick release feature of the flexible supply connection to allow the user to easily attach and remove the handpiece/coupler combination from the flexible supply connection.
As the handpiece requires a supply of air, water and in some cases, a supply of electricity, the coupler at the proximal end of the handpiece facilitates the supply of the required resources from the flexible supply connection. The coupler includes seals typically positioned on its cylindrical portion to isolate water, air and optional electrical power that may be provided. The flexible supply connection typically is a flexible hose that attaches to the coupler. The hose provides air, water and electricity to the handpiece through the coupling. A flexible supply end is typically affixed to the flexible supply, such as a hose connector using a threaded ring, configured to mate with the coupler supply end, and thus also meets the applicable ISO standard. The coupler may be a swivel coupler that rotates as the handpiece is moved by the dental professional so that the rotational motion of the coupler and flexible supply connection is substantially independent that of the handpiece, thereby providing the dental professional with some freedom of movement as he/she manipulates the handpiece in the patient's mouth. Couplers are typically a proprietary design which only fits the handpieces of one manufacturer. More specifically, since the supply end portion of the coupler is made in accordance with an industry standard that allows it to mate with the flexible supply connection, it is the cylindrical portion of the coupler that interfaces with the handpiece that incorporates the proprietary design. This precludes the use of a universal replacement coupler for the coupler that utilizes a proprietary design
The axis of the coupler and the axis of the handpiece are in substantial axial alignment (i.e. either substantially coaxial or substantially parallel). The end of the flexible supply connection is rigid, so that the flexible portion of the hose effectively begins a slight distance from the handpiece/coupler/supply interfaces. The result is that the end of the flexible supply or hose also is in substantial axial alignment with the coupler. The forces from the weight and flexural resistance of the hose are thus applied at a point well behind the area in which the dental professional grips the handpiece, resulting in a moment arm that increases the strain on the dental professional's hand. In addition to temporary fatigue and wrist strain from short periods of use, over long periods of time, this substantially continuous strain can lead to chronic problems such as carpal tunnel syndrome or other hand related problems.
What is needed is a coupler supply end interface that reduces the strain on the dental professional's hand, while still allowing the coupler supply end interface to meet the industry standard.